Forensic Botany

Principles and Applications to Criminal Casework

Heather Miller Coyle, Heather Miller Coyle

• Publisher: CRC Press
• Year: 2004
• ISBN:
  9781135504649
• Edition: 1
• Topic: Law
• Subtopic: Forensic Science
• Index: Law

Increasingly, forensic scientists use plant evidence to reconstruct crimes. The forensic aspects of this subject require an understanding of what is necessary for botanical evidence to be accepted in our judicial system.Bringing together the latest information into a single resource, Forensic Botany: Principles and Applications to Criminal

1
Introduction to Forensic Botany

HEATHER MILLER COYLE

Contents

1.1 Plants Are Ubiquitous

1.2 Plants as Poisons

1.3 Plants as Trace/Transfer Evidence

1.4 Forensic Botany

1.5 Plants in Our Society

1.5.1 Food

1.5.2 Fiber

1.5.3 Medicine

1.5.4 Beauty

1.5.5 Recreation

1.5.6 Law Enforcement

General References

1.1
Plants Are Ubiquitous

Plants are ubiquitous in nature, essential for all human and animal existence. They are critical to the earth’s atmosphere and to other forms of life, and serve a function as intermediaries by converting solar energy into complex molecules. While some plants provide a source of food, others provide fiber, medicine, and aesthetic pleasure. The average person enjoys plants in a multitude of ways throughout the day. The pure green of the golf course, the sweet smell of a rose, the calming effect of chamomile tea, a glass of wine from a superior grape cultivar, and the comfort of well-worn cotton blue jeans are just a few examples. These are common, pleasant examples of plant usage in our society, but what happens when plants become associated with criminal activities?

1.2
Plants as Poisons

Many homicides, accidental deaths, and suicides have occurred through the inappropriate and deliberate use of plants to achieve harmful effects. Many substances, including common table salt, can be considered poisonous if consumed in sufficient quantity. The use of poison to commit murder is more prevalent with women, but plenty of documented cases exist for both sexes. The list of plants that have been used for both deliberate and accidental death is lengthy. A few examples include the following: hemlock, wolfsbane (monkshood), belladonna (deadly nightshade), tobacco (nicotine), nux vomica tree (strychnine), foxglove (digitalis), and castor bean (ricin). The early nineteenth century was the “fashionable period” for murder by poisoning. In fact, poisoning was so common that many people employed food tasters to sample their food before ingestion as a safeguard to their health.

1.3
Plants as Trace/Transfer Evidence

In addition to the toxic properties of some plants, botanical samples can serve as key pieces of trace evidence. Forensic botany is a subdiscipline of forensics that is still, perhaps, in its infancy. It is, however, becoming a more common tool as law enforcement agencies, forensic scientists, and attorneys become more familiar with the applications of plant material to casework. Also, as plant research continues in academic and private research laboratories, new tools are being developed that can be eventually applied to forensic botanical evidence to aid in criminal and civil cases. In addition, these new tools can be important for national security and historical issues. Plant evidence is commonly associated with crime scenes and victims; typically, stems, leaves, seeds, flowers, and other identifiable parts of plants are useful as trace botanicals. One might imagine that the chemical composition of herbs, spices, condiments, beverages, fibers, medicines, plant resins, and oils, for example, may be useful for forensically relevant plant “signature” programs just as those used in drug chemistry (e.g., cocaine, heroin) if appropriate databases can be constructed.

1.4
Forensic Botany

Forensic botany is a marriage of many disciplines and results ultimately in their application to matters of law. The botanical aspects of forensic botany include plant anatomy, plant growth and behavior, plant reproductive cycles and population dynamics, and plant classification schemes (morphological and genetic) for species identification. The forensic aspects require an understanding of what is necessary for botanical evidence to be accepted as evidence in our judicial system. Forensics requires recognition of pertinent evidence at a crime scene, appropriate collection and preservation of evidentiary material, maintenance of a chain of custody, an understanding of scientific testing methods, validation of new forensic techniques, and admissibility criteria for court. The goal of this textbook is to provide basic knowledge to anyone wishing to study or utilize botanical evidence in forensic casework. The framework for plant biology and general forensics is described in the first few chapters of this textbook. After providing a scientific foundation for the field of forensic botany, we describe applications and casework examples in detail. A wide variety of forensic botany examples include the use of several plant parts (leaves, flowers, pollen, wood) and plant species. Almost as varied are the scientific methods utilized in forensic botany, and these methods range from simple techniques (e.g., light microscopy) to more technical molecular biology techniques (e.g., DNA sequencing). Plants have been used as evidence in criminal cases for kidnapping, child abuse, hit-and-run motor vehicle accidents, drug enforcement, homicide, sexual and physical assault, the establishment of time of death, and verification of an alibi. In addition, new applications are under development to use plant material in forensics as “tracers” to aid in the identification of missing persons, to track drug distribution patterns, and to link bodies to primary crime scene locations after they have been dumped at secondary sites.

1.5
Plants in Our Society

To understand the widespread application and potential utility of plants in forensics, we discuss a few brief examples of plant usage in human society. As these examples are presented, consider the number of plant-based items that may be found on your person, among your private possessions, and in your home and workplace—and consider, one day, that they may be useful as critical trace evidence.

1.5.1
Food

Apples are generally considered to be a wholesome, healthful addition to the daily diet as a good source of vitamins and fiber (Figure 1.1). In actuality, this concept was promoted by the apple industry in response to the renouncement of apples by Carry Nation as part of the Prohibition Act. The Women’s Christian Temperance Union was opposed to apples because they were, in part, responsible for alcohol use on the frontier. In the early 1900s, the apple industry

Figure 1.1 Apples are an edible mainstay of many people’s diets and have been successfully swabbed for suspect DNA profiles after burglaries.

began promoting the healthful benefits of apples, and today, we have many apple cultivars to choose from at our markets. Interestingly, burglars often sample fruit and other foods in the homes they are invading while pilfering goods.

1.5.2
Fiber

One prevalent clothing fiber in our society is cotton. Cotton comes from the elongated epidermal hairs on the seeds of the Gossypium hirsutum plant. Prior to mechanized harvesting of cotton fibers, flax (Linum usitatissimum) was the most common fiber plant for the textile industry. Flax fibers, unlike cotton, are sclerenchyma fibers from the stem of the flax plant. Flax fibers are commonly woven into linen, and certain cultivars are used to produce cigarette papers and linseed oil. As trace evidence, the source of clothing, carpet fibers, rope, twine, and threads can be useful for associating a victim to a suspect or individuals back to a primary crime scene for an investigative lead.

1.5.3
Medicine

Herbal remedies and folklore investigations to identify active chemical components have long been part of human culture and have played an important role in the discovery of useful medicinal compounds (e.g., aspirin). In addition, well-preserved stomach contents from ancient human remains have yielded insight into rituals involving herbs and food. For example, in 1984, a peat cutter near Manchester, England, discovered a well-preserved human leg and called in the police to investigate. The body of Lindow Man was recovered, and radiocarbon dated to approximately A.D. 50–100, and he was determined to be a member of the Celtic tribes. The archeobotanists used electron spin resonance (ESR) applications to examine the gut contents of the preserved man and discovered burned, unleavened barley bread and put forth the concept of a sacrificial victim during the Feast of Beltain. This feast was celebrated on May 1 as a pagan ritual, and it is thought that the unlucky person to choose the blackened bread was designated as the sacrifice.

1.5.4
Beauty

Plants are key components in many herbal shampoos, soaps, cosmetics, and perfumes. Not only are botanicals used in human cosmetics and have appealing scents, but they beautify our environment as well. The Dahlia flower, for example, has an unusual history (Figure 1.2). Originating from Mexico and called Cocoxochitl by the Aztec Indians, it was discovered and seeds were sent to a French priest studying botany in Madrid, Spain. It was then renamed after Dr. Dahl, a student of botany, who was interested in its tuberous roots as a potential food source rather than for the showy blossoms that gardeners covet today. After planting in English greenhouses, most of the tubers rotted away until the dahlia was improved by breeding efforts in the late 1800s and became accessible to gardeners everywhere. The American Dahlia Society recognizes 12 groups of cultivars based on the head morphology and the flowers, and suggests that most modern cultivars were derived from the parental Dahlia pinnata and Dahlia coccinea.

1.5.5
Recreation

The American obsession with green lawns can be visualized in the numerous golf courses, city parks, and extensive front and backyards that are ingrained parts of suburban life. Prior to the Civil War, few Americans had lawns. However, in the 1950s, the term “lawn” was used in reference to a portion of land kept closely mown in front or around a house. In the 1950s, turfgrass breeding programs gave rise to several new grass varieties that offered improved heat, drought, and disease resistance. In the 1970s and ’80s, lawn specialists began recommending blends of grasses (e.g., fescue, bluegrass, perennial ryegrass) rather than a monoculture of a single grass species. Today, American homeowners spend enormous capital and energy on achieving a perfectly

Figure 1.2 The dahlia is one example of a common horticultural plant found in landscaping across the U.S. Pollen from flowers can often be useful for providing additional evidence if found on suspect clothing.

groomed, green lawn as a setting for their homes. In fact, an entire lawn-care industry has developed around this particular aspect of suburban homes. Grass samples may be one of the most abundant types of botanical evidence found at crime scenes simply due to the American obsession with the lawn.

1.5.6
Law Enforcement

Plants may be present as biological evidence in many ways:

• Seeds caught and carried in a pant cuff
• Grass stains on a dress after a sexual assault
• Plant leaves and stems snagged and carried in a vehicle’s undercarriage, grill, wheel wells, hood, or trunk
• Stomach contents with vegetable matter to aid in verification of an alibi
• Use of pollen to date the burial of skeletal remains in a mass grave

All of these examples and more can assist the forensic community in associating a person to an object, a person to a crime scene, or a suspect to a victim. “Every criminal leaves a ‘trace’ (evidence)” is a phrase with some accuracy. That “trace” may very well be biological plant material. The remaining chapters w...